1. Field of the Invention
The present invention relates to an LCD (Liquid Crystal Display) test system, and more particularly to an in-line LCD test system capable of promptly and accurately testing LCDs.
2. Description of the Conventional Art
Liquid crystal display (LCD) has generally a structure in which liquid crystals (LCs) are sandwiched by two glass substrates having transparent electrodes thereon. The LCs are compounds which have intermediate states between a liquid and a solid having molecules regularly arranged. The LCs are organic compounds having a long and thin rod-like molecular structure, with optical and dielectric anisotropic characteristics.
The LCDs are non-emissive types of display devices, and thus require a light source located outside a panel. The LCDs provide thinner flat panel than that of a CRT and achieve a full-color display, which lead to rapid practical use thereof.
The LCDs may be greatly classified into three types of TN, GH and TFT LCDs.
A TN type of LCD uses twisted nematic materials as LCs, widely used for displays, which are put into between two glass plates, each having transparent electrode films thereon. The production of such a TN type of LCD includes special processing called a rubbing processing applied to surfaces of the glass plates.
Secondly, a GH type of LCD is manufactured to permit a color display with the above-mentioned TN LCs as host to which dye is added as a guest. Finally, a TFT LCD is structured to have: a glass substrate on which pixels, each including a transistor and a display pixel (transparent) electrode, are arranged in a matrix manner and which transparent common electrodes are attached to; another opposing glass substrate having a color filter with a sequential arrangement of three primary colors in a matrix manner, each color being disposed corresponding to respective pixels, and transistors implemented by thin film FETs (Field Effect Transistors) for the purpose of driving a LC; and the LC inserted between said two glass plates.
Recently, thin film transistor liquid crystal display devices (TFT LCD) having lower power consumption and lightweight advantages have been used as display devices for various electronics, such as electric calculators, telephones, electronic organizer, notebook computers, etc. Also, a transition from 7-segment displays to dot-matrix displays results from an advance in LCD manufacturing and driving techniques, wherein the dot-matrix displays constitute a main trend of displays.
Since the number of electrodes increase in proportion of the amount of information to be displayed, the circuit connections between the LCD driving devices and the LCD become complicated. Accordingly, it is necessary to provide an apparatus for testing the circuit connections of the LCD.
A prior art LCD test system, mainly designed to test the 7-segment displays, conducts tests as to whether each segment of the LCD is properly connected or not, through the use of the key inputs to the test system.
However, a problem exists in that it cannot be tested all of segments of the dot-matrix type of the LCD as main displays currently used.
Therefore, it is an object of the present invention to provide an LCD test system capable of promptly and accurately testing LCDs and of minimizing failure of electrical contact to a tester.
According to the present invention, there is provided an LCD test system comprising: a main frame; an index stage located adjacent to the main frame and having a stacker for supplying a plurality of LCD cassettes; a pre-aligner for aligning the LCD supplied from the stacker of the index stage; a carrier for transferring the aligned LCD so as to test the LCD; and a work table unit for setting such that the LCD transferred by the carrier is tested.
According the LCD test system thus constructed, the LCD to be tested is automatically aligned, transferred and electrically contacts to the probe pins by the pre-aligner, the carrier and the work table unit, respectively. A series of such processes reduces the time required to test the LCD and increases in an test accuracy.